Field of the Invention
The present invention relates to a method and a system for releasing a catching of a locking pin, and more particularly, to a method and a system for releasing a catching of a locking pin for solving a problem that a continuous variable valve timer (CVVT) itself including a cam shakes since the locking pin is actually loosed from a locking pin hole during a process of performing a control logic for releasing the locking pin in the case in which the locking pin is caught with the locking pin hole, and as a result, when the releasing is completed, a cam is rotated in a direction which is opposite to a direction in which the cam originally intends to be rotated.
Description of Related Art
In order to assist in understanding the present invention, a locking pin of a CVVT will be first described as follows.
In general, the CVVT is a system of continuously changing an open or close timing of a valve by changing a phase of a cam shaft depending on an RPM of engine and a load state of a vehicle.
The continuous variable valve timer 101 of a vehicle according to the related art generally includes a crank angle sensor sensing a rotation angle of a crank shaft, a cam angle sensor sensing a rotation angle of a cam shaft 104, a variable valve timing unit 150 connected to one side of the cam shaft 104 by a timing belt and advancing or retarding the cam shaft 104, and an electronic control unit (ECU) controlling an oil control valve 108 so as to supply oil to an advance chamber 111a or a retard chamber 111b of the variable valve timing unit 150 based on signals of the crank angle sensor and the cam angle sensor, as shown in FIG. 1.
The variable valve timing unit 150 includes a stator 110 connected to the crank shaft by the timing belt so as to receive rotational force of the crank shaft, and a rotor 120 of a vane shape which is integrally coupled to the cam shaft 104 and is rotated relative to the stator 110.
The stator 110 is provided with a chamber 111 which is divided into the advance chamber 111a and the retard chamber 111b by the rotor 120. If the oil is supplied to the advance chamber 111a through an oil control valve 108, a phase difference is generated between the rotor 120 and the stator 110 and the cam shaft 104 is rotated, thereby changing a timing of the valve.
Of course, if the oil is introduced into the retard chamber 111b through the oil control valve 108, a phase difference is generated between the rotor 120 and the stator 110 in a direction opposite to that described above, thereby retarding the timing of the valve.
The rotor 120 is provided with a locking pin 131 so that the rotor 120 is wound around the stator 110 when the engine is stopped, and the stator 110 is provided with a pin catching part (not shown) with which the locking pin 131 is caught.
However, in the continuous variable valve timer 101 according to the related art as described above, when the engine is stopped, the locking pin 131 may not be properly caught with the pin catching part, or may not be moved by a physical constraint even though using an electronic control, or may be stuck by surrounding foreign materials.
Meanwhile, in order to electronically control an operation of a lock/unlock for a locking pin hole formed in the rotor of the locking pin, the ECU controls the operation of the lock/unlock while switching on/off power of a solenoid valve.
However, if the cam is operated before the locking pin is completely loosed from the locking pin hole, the locking pin is physically caught with peripheral devices of the locking pin or is stuck by the foreign materials, and consequently the locking pin may not be loosed. As such, in the case in which the locking pin is not loosed, since the CVVT is not operated and a position of the cam does not smoothly follow a set target value, an engine warning light is turned on due to the following defect. As a result, the driver should go to a repair shop for directly receiving an after service.
A state showing a problem in which the locking pin is caught with the locking pin hole formed in the rotor of the locking pin is shown in FIG. 2.
As shown in FIG. 2A and FIG. 2B, after the locking pin 131 is released from the locking pin hole by being moved to a lower direction of the locking pin hole, the control of the CVVT is first performed and the locking pin should be rotated in an advance direction or a retard direction. However, in the case in which the control of the CVVT is first performed by supplying the oil to the oil control valve before the locking pin 131 is released, since side rotational force (side force) by force trying to rotate is greater than unlock force which is downward force of the locking pin, the locking pin is not released.
Consequently, as described above, in the case in which the locking pin is not loosed, since the CVVT is not operated and a position of the cam does not smoothly follow a set target value, an engine warning light is turned on due to the following defect. As a result, the driver should go to a repair shop for directly receiving an after service.
In order to solve the above-mentioned problems, there is a method in which the locking pin is released by canceling ‘side force’ while shaking the CVVT in the advance or retard direction. However, as shown in FIG. 3, the CVVT may shake in a direction which is opposite to a target direction of the CVVT as shown in ‘A’ in the instant at which the locking pin is actually released.
Therefore, various aspects of the present invention are directed to providing a method and a system for releasing a catching of a locking pin capable of preventing the CVVT itself including the cam from being shaken by rotating the CVVT in a direction which is opposite to the target direction of the CVVT even in the instant at which the locking pin is actually released.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.